Fixed the Markdown issue #2

It's not ideal. Right now I'm just reverting to html.basic instead of html.markdown for the Markdown syntax highlighting. This fixes issue #2 and still allows for basic html highlighting inside a Markdown block, but it obviously removes Markdown specific support.

The longer term solution is to roll my own Markdown highlighting definition, which also allows me to add support for the talked about Markdown templating discussed on the Elm mailing list